In general, when a medicine stored in an intravenous bottle (e.g. Ringer bottle) or the like is injected into a patient's blood vessel, the medicine is injected into the patient's blood vessel at a flow rate which can be varied according to a storage amount of the medicine. In this regard, when it is necessary to inject a liquid medicine such as a special injection medicine, including an anti-cancer medicine or an antibiotic, to a patient, the desired amount thereof should be injected consistently and continuously depending on a patient's condition. If the amount of special injection medicine necessary for a patient is not consistently and continuously injected, there is a risk of the occurrence of shock.
In a conventional regulator for regulating a flow rate of a liquid medicine, the regulator is generally rotated upward or downward to change a cross-sectional area of a tube, thereby regulating the amount of liquid medicine flowing to a syringe needle. However, the conventional regulator has a problem in that it is difficult to finely regulate the flow rate of liquid medicine.
In consideration of such a problem, PCT Patent Publication No. WO 03/066138 A1 discloses a liquid supply apparatus for pushing out a liquid medicine contained in a cylinder by a piston to inject the liquid medicine to a patient. In order to inject the liquid medicine to the patient consistently and continuously, the liquid supply apparatus includes a gas supply apparatus which generates gas and applies a constant pressure of the generated gas against a piston to gradually push the piston, and a pressure regulating valve which can uniformly regulate the pressure of the generated gas in the gas supply apparatus by discharging high pressure outside which may be temporarily generated from the gas supply apparatus.
The liquid supply apparatus is excellent, but it can be improved further in common with other excellent technologies. That is, the conventional liquid supply apparatus has a need for improvement in that it is inconvenient to install the pressure regulating valve inside the gas supply apparatus and in that manufacturing cost is increased due to a complicated structure of the pressure regulating valve. Moreover, the pressure regulating valve has a limit in application to various medicine injection devices because it can be applied only to medicine injection devices each of which has a gas supply apparatus for generating gas.
Therefore, in the technical field of the present invention, there are unceasing demands on the improvement of a medicine flow rate regulator, which can prevent a flow rate of a liquid medicine to be injected to a patient from exceeding a predetermined flow rate needed for a patient and control the flow rate of the liquid medicine to be uniformly maintained, and can be applied to intravenous bottles or various medicine injectors and be easily installed in them.